Offset printing apparatus cleaner

ABSTRACT

The invention relates to a device for cleaning a printing cylinder and comprising a roller for applying ink solvent to the cylinder and a device for wiping excess solvent around the cylinder to be deposited on a solvent absorbent strip attached to the cylinder. The volatile solvent may subsequently evaporate to leave the strip once more absorbent.

D United States Patent 1 1 3,592.1 36

|72| Inventor ThomuG. Selma: [56] References Cited -t UNITED STATESPATENTS 2.363,8l7 11 1944 Taylor 101/425 ux 2,691,344 10/1954McMullen..... 101/425 e 2,944,484 7/1960 Bruce 101 425 [73] gfi 'k f3.089.415 5/1963 Grembecki et 111.. 101/425 [32] Mom Jan 3.094.0686/1963 Gericke .1 101/425 y 3.I44.826 8/1964 Lang etal. 101/425 [33]Great Britain 3 881/68 FOREIGN PATENTS 1,093,803 l0/l958 Germany l0l/425Primary ExaminerRobert E. Pulfrey Assistant Examiner-C. CoughenourAnomzy-Cushman, Darby and Cushman [54] OFFSET PRINTING APPARATUS CLEANERClaims 3 Damn Figs ABSTRACT: The invention relates to a device forcleaning a [52] US. Cl 101/425, printing cylinder and comprising aroller for applying ink sol Nil/ 423. l0ll4l5.l vent to the cylinder anda device for wiping excess solvent [5H Int. Cl B4lf35/00 around thecylinder to be deposited on a solvent absorbent [50] Field of Feardll0l/l23 strip attached to the cylinder. The volatile solvent may sub-125 sequently evaporate to leave the strip once more absorbent.

PATENTEUJULIBIEWI 3.592.136

SHKET 1 OF 2 A ttorneyg PATENIEU M1319?! SHEET 2 OF 2 I nuenlor MsGnu-9g silman a, 05mm, 0%, a Mm A llorney:

OFFSET PRINTING APPARATUS CLEANER The present invention relates to animprovement in or relating to printing apparatus, and more particularlyto an improved device for cleaning a cylinder surface such as theblanket of offset printing apparatus, after a printing cycle has beencompleted. For example, in offset printing apparatus if a short runprinting cycle has been carried out using a particularly printing plate,and it is then desired to change the plate, the new plate cannot be useduntil the previous impression on the blanket has been removed so thatthe fresh impression may be featured clearly on the surface. The blanketmay be cleaned by applying a solvent to the surface of the blanket forexample with a cloth so that ink is absorbed and transferred to thecloth or other solvent applying means. However, residual cleaningsolvent must thus be allowed to evaporate from the surface of theblanket before printing may recommcnce.

According to the present invention we provide printing apparatusincluding a cylinder, means for selectively applying ink solvent to thecylinder solvent absorbent means attachable to the cylinder, and asolvent wiping means selectively operable to wipe ink solventcircumferentially of the cylinder towards the solvent absorbent means.Preferably the cylinder has a part of its surface adapted to receive aprinting blanket, the solvent absorbent means is arranged to extendlongitudinally of the cylinder at one end of the blanket receiving partof the surface thereof, and the solvent wiping means is mounted on asupport adapted to be held stationary with respect to the axis of thecylinder. Thus the arrangement pro vides that, upon rotation of theblanket cylinder after cleaning, residual solvent or inky solution onthe blanket is wiped clear by the wiping means and is moved round to theend of the blanket adjacent said absorbent means, the wiping means whendepositing the residual solvent in a position from which it may readilybe absorbed by the absorbent means,

The apparatus of this invention may be used with any print ing machine,but is particularly suitable for use with an offset machine having anautomatic blanket washup attachment including blanket cleaning means forintroducing cleaning solvent to the surface of the blanket. In such adevice the ink is readily transferred from the blanket to the solventintroducing cleaning device, residual solution or solvent beingdeposited adjacent said absorbent means.

Conveniently said absorbent means may comprise an elongate strip ofabsorbent material extending longitudinally of the cylinder and having aperipheral extent less than that of a recessed portion of the cylindersurface which portion normally receives the end clamps of the blanket.Preferably the absorbent strip may be mounted radially inwardly on apartcylindrical solvent permeable sheet, said sheet forming acontinuation of the cylindrical surface of the blanket receiving part ofthe cylinder. Desirably said permeable sheet may be in the form of anelongate plate having passages extending therethrough in directionsradial with respect to the cylinder. conveniently said absorbent stripmay comprise a sheet of sponge material. Alternatively the absorbentmaterial may be formed synthetic plastics material. Desirably saidwiping means may comprise a blade extending longitudinally of thecylinder and mounted on a frame pivotable between an operative positionin which the blade contacts the surface of the cylinder and aninoperative position in which the blade is clear of the surface of theblanket. The blade may be flexible and is preferably formed of rubber.Conveniently the solvent applying means may comprise a roller having anabsorbent surface adapted to be placed in contact with the cylinder. Thecleaning solvent applying roller may be mounted on the same frame memberas the wiping blade. If desired, the frame may be pivoted to andretained in an intermediate position, between said operative andinoperative positions, in which the cleaning solvent applying roller isfree from contact with the blanket but the blade is still in contacttherewith. Suitably the cleaning solvent applying roller may bepositioned above a reservoir of cleaning solvent so that the bottom partof the applying roller is immersed in the cleaning solvent within thereservoir.

Advantageously means may be provided for rotating the cleaning solventapplying roller when in contact with the cylinder, and preferably saidapplying roller rotating means causes rotation of the applying roller inthe same sense as the rotation ofthe cylinder during the cleaning cycle.

In order that the present invention may more readily be understood, thefollowing description is given, merely by way of example, of oneembodiment ofthe invention, in the form ofa blanket cylinder cleaningdevice for use with offset printing apparatus. Reference will be made tothe accompanying drawings in which:

FIG. 1 shows a blanket cleaning device of the present invention, whenboth a cleaning roller and a cleaning blade are in contact with theblanket to be cleaned;

FIG. 2 shows the device of FIG. 1 in an intermediate position in whichthe blanket cleaning roller is in an operative position but the cleaningblade is still operating on the surface of the blanket cylinder; and,

FIG. 3 is a view, similar to FIG. 2, but showing the blanket cleaningdevice in its inoperative position where both the cleaning roller andthe cleaning blade are clear of the surface of the blanket cylinder.

Referring now to the drawings, and in particular to FIG. 1, there isshown a transverse sectional view ofa cleaning device associated withthe blanket cylinder of an offset shaft device. is cylindrical spongecleaning roller 1 rotates in the an ticlockwise sense in contact with ablanket plate 2 on the surface of a blanket cylinder 3. The cleaningdevice further includes a flexible wiper blade 4 attached at the freeend of a bracket 5 secured to the frame 6 of the cleaning device. Thecleaning device further includes a cleaning solvent tank 7 containingcleaning fluid 8 which is entrained by the rotation of the spongesurface 1 on the cleaning cylinder 9 mounted on a shaft 10 journaledwithin the frame 6 of the cleaning device. The shaft 10 is driven forrotation in the anticlockwise sense by suitable driving linkage which isnot shown in the accompanying drawings.

The cleaning blade 4 consists essentially of a single main blade 40arranged so that, in the operative position of the blade assembly, theblade 40 wipes the cylindrical surface of the blanket 2, and furtherthat a reinforcing strip 4b placed behind the main blade 4a serves toincrease the flexural strength of the blade 4a to help resistdeformation of the blade 40 caused by frictional contact of itsoperative edge with the surface of the blanket 2.

The blanket cylinder 3 is driven for rotation in the anticlockwise senseabout shaft 11 by a suitable driving mechanism not shown in thedrawings. The leading edge of the blanket 2 is clamped at 13 to thecylinder 3 and a similar clamp 14 retains the trailing edge of theblanket fixed with respect to the cylinder 3. As can be seen from FIG.1, the trailing edge of the blanket 2 passes in tension over a sharpedge 15 of the cylindrical surface of the roller 3 and, due to thetension in the blanket 2 exerted by the blanket trailing end clamp 14,the trailing part of the blanket extends in a straight line along asubstantially chordal direction with respect to the cylinder 3 betweenthe sharp edge 15 an the clamp 14. However, a part cylindrical plate 16is clamped in position so that it forms a continuation of thecylindrical surface of the blanket 2 radially outward with respect tothe trailing end clamp 14. The arcuate plate 16, which is mounted justradially outwardly ofa pad of sponge material 25, is perforated bypassages 17 extending along directions radial of the cylinder 3. Theplate 16 is retained in position by a Z-shaped bracket 18 secured to theclamp-containing well of the cylinder 3 by means of a stud 19 extendingradially outwardly from the well and a nut 20 threadedly engageable onthe stud so as to clamp one limb of the Z-shaped clamp 18 against thesurface of the well.

A set of countersunk bolts 21 extending through and received in suitablyarranged recesses within the arcuate plate 16 bears against the bracket18 but with a flat spacing nut 24 therebetween. Each spacing nut 24 isalso threadedly engageable on the associated bolt 21 so that the orderof assembly of the plate 16, bracket 18 and bolts 21 will be as follows.Each bolt 2] is first inserted, in a radially inward direction, into thecorresponding recess in the plate I6, each flat spacing nut 24 thenbeing threadedly secured on its associated bolt 2l so as to clamp thebolt with respect to the plate 16. At this stage the sponge pad 25 ispositioned in contact with the plate I6 so that the spacer nutsassociated with the various bolts 21 are received in suitable aperturesin the sponge pad 25. After this the plate [6, together with its variousbolts 2l, is brought into engagement with the Z-shaped bracket 18 byengagement of the bolts 21 within the various apertures 22 of theZ-shaped bracket [8. Finally each bolt 21 is provided with a washer anda clamping nut 23 which is then tightened and the structure thus madesecure.

FIG. 1 shows the cleaning device in its operative position in which thesponge surface 1 of the cleaning cylinder 9 is in con tact with andexerts a scrubbing action against the blanket 2 during rotation of theshafts l and II. Furthermore the scraper blade 4 is shown as contactingthe surface of the blanket 2.

In order to withdraw the cleaning device from contact with the blanketthe main frame 6 of the cleaning device is pivotally mounted on a shaft26 secured to the frame of the offset printing apparatus, and pivotablemovement of the frame 6 about the shaft 26 in a clockwise direction willwithdraw firstly the cleaning cylinder assembly and subsequently theblade from contact with the blanket 2.

FIG. 2 shows an intermediate position in which the frame 6 of thecleaning device has been rotated through a small angle in the clockwisedirection so that the surface of the cleaning sponge l is clear of theblanket 2 and the blade 4 is still scraping the surface of the blanket.

In FIG 3 further clockwise rotation of the cleaning device has takenplace, and both he cleaning sponge I and the blade 4 are now free fromcontact with the blanket, and normal printing may take place.

By way of further explanation, one cleaning cycle of the apparatusillustrated will now be described, commencing with the application ofcleaning fluid and ending with the preparation of the blanket forfurther printing.

When it is desired to clean the blanket 2 of an offset printing devicethe frame 6 of the cleaning device is pivoted in an an ticlockwisedirection until the sponge surface 1 ofthe cleaning cylinder 9 and theblade 4 are in contact with the surface of the blanket, as shown inFIG. 1. The pivotal movement ofthe frame 6 about the shaft 26 may beachieved either by a manual control lever moved by the operator of theapparatus, or by suitable automatic programming devices which requiremerely a single wash control to be actuated. For example, the movementof the frame may be effected by driven rotation of a suitable camengaging with a cam follower associated with the frame.

The shafts l0 and II are then rotated in the anticlockwise direction sothat a scrubbing action takes place between the sponge surface I and theblanket 2, cleaning solvent being lifted from the tank 7 by the sponge 1and being deposited on the cylindrical surface of the blanket 2 anddissolving ink therefrom, the inky solution being transferred to thesponge I by means of which it is carried in an anticlockwise directiondown into the tank 7. The blade 4, positioned just downstream of thepoint of contact between the sponge and blanket 2, then wipes clean thesurface of the blanket 2 by removing the residual cleaning solvent, justdeposited on the surface of the blanket by the sponge I, together withany ink absorbed by the solvent. The washup cycle is preferably carriedout for three to four revolutions of the blanket cylindcr, since theparticularly advantageous arrangement described will clean the blankct 2thoroughly in only these few rotations of the cylinder 3.

During the washing rotations of the cylinder 3 the cleaning solventwiped by the blade 4 tends to build up just below the wiping edge of theblade and, as the blanket cylinder rotates, the solvent and dissolvedink is moved relatively to the surface of the cylinder 3 towards thechordal portion of the trailing end of blanket 2, and is then wiped onto the arcuate surface of the perforated plate 16. The solvent anddissolved ink may then pass through the perforations of the plate I6 andare absorbed by the sponge 25.

At this stage, since solvent has been deposited and removedsimultaneously, there will be a slight residue ofink and solvent on thesurface of the blanket since almost invariably the blade 4 would not beable to cope with clearing the surface of the blanket 2 completely whilesolvent is still being deposited by the sponge 1. Accordingly the frame6 of the cleaning device is pivoted in a clockwise direction through asmall angle until it reaches the intermediate position, illustrated inFIG. 2, in which the blade 4 is still in contact with the surface of theblanket 2 but the sponge I is now completely free from contact with theblanket. One or two revolutions of the blanket cylinder 3, while thecleaning device is in this intermediate position, will be sufficient toremove the residue of the ink and solvent.

Now the blanket will be completely clean and will be dry since the blade4 will have wiped all the cleaning fluid and dis solved ink onto thesponge 16 at the trailing end of the blanket. The cleaning device maythen be rotated further in the clockwise direction until both the spongeI and the blade 4 are free from contact from the blanket 2 and normalprinting may be resumed.

Since the solvent chosen is a volatile material the sponge 25 will tendto dry out during the early part of the next printing cycle so that bythe end of the printing cycle, when a further blanket washup cycle isrequired, the sponge 25 will once again be dry and ready to absorb theink and cleaning fluid deposited thereon by the blade 4 of the cleaningdevice.

The plate l6, although described as being a cylindrical plate withperforations in the form of bores 17 extending in the radial directionwith respect to cylinder 3, may be perforated by means of slits runningin the radial direction and extending longitudinally of the plate, bytwo sets of intersecting diagonal extending slits forming a grid ofslits across the plate, or by being constructed from a suitable porousmaterial such as sintcred metal. Clearly the precise nature of the inkand solvent permeable plate 16 does not affect the scope of theinvention, the only requirement being that ink and solvent are capableof passing from the outer cylindrical surface of the plate 16 on to thesponge 25.

We claim:

I. Printing apparatus including frame means, a cylinder carried by saidframe means, an ink receiving surface formed on said cylinder and meansfor cleaning ink from the cylinder, such cleaning means comprising:

a. means supported by said frame means for applying ink solvent to saidcylinder,

b. solvent absorbent means attached to said cylinder ink receivingsurface; and

c. means supported by said frame means for wiping excess solventcircumferentially of said surface towards said solvent absorbent meansv2. Printing apparatus according to claim I, and including:

d. part cylindrical demountable blanket means attached to the cylinderand forming said ink receiving surface, said solvent absorbent meansbeing arranged to extend longitudinally of said cylinder along one edgeof said blanket means; and

. pivotable support means supported by said frame means and carryingsaid solvent wiping mean for movement between a solvent wiping positionand an inoperative position.

3. Printing apparatus according to claim 2, and including:

f. recessed surface means on said cylinder for receiving the end clampsof said blanket means, and

g. an elongated strip of absorbent material within said recessed surfacemeans, constituting said solvent absor bent means and extendinglongitudinally of the cylinder and having a peripheral extent less thanthat of said recessed surface means.

4. Printing apparatus according to claim 3, and including partcylindrical solvent permeable means having the same radius and center ofcurvature as said blanket means, said absorbent strip being mounted onsaid solvent permeable means radially inward thereof.

5 Printing apparatus according to claim 4, wherein said sol ventpermeable means comprises:

h. an elongate plate, and

j. passage means extending through said plate in directions radial withrespect to the cylinder 6. Printing apparatus according to claim 2,wherein said wiping means comprises a wiper blade extending parallel tothe axis of said cylinder, and wherein the inoperative position of saidpivotable means is a position in which said wiper blade is withdrawnfrom contact with said cylinder.

7. Printing apparatus according to claim 2, wherein said solventapplying means comprises:

k. a roller;

l. solvent absorbent surface means on said roller;

m. solvent bath means for introducing ink solvent to said ab sorbentsurface means; and

n. means for pivotally mounting said roller for movement between asolvent applying position in contact with said cylinder and aninoperative position out of contact with said cylinder.

8. Printing apparatus according to claim 7, wherein said pivotablesupport means also carries said solvent wiping means.

9. Printing apparatus according to claim 7, and including means forrotating the solvent applying roller when in contact with the cylinder.

10. Printing apparatus according to claim 9, wherein said rollerrotating means drives the applying roller for rotation in the samedirection of rotation as that of the cylinder in use of the apparatus.

1. Printing apparatus including frame means, a cylinder carried by saidframe means, an ink receiving surface formed on said cylinder and meansfor cleaning ink from the cylinder, such cleaning means comprising: a.means supported by said frame means for applying ink solvent to saidcylinder; b. solvent absorbent means attached to said cylinder inkreceiving surface; and c. means supported by said frame means for wipingexcess solvent circumferentially of said surface towards said solventabsorbent means.
 2. Printing apparatus according to claim 1, andincluding: d. part cylindrical demountable blanket means attached to thecylinder and forming said ink receiving surface, said solvent absorbentmeans being arranged to extend longitudinally of said cylinder along oneedge of said blanket means; and e. pivotable support means supported bysaid frame means and carrying said solvent wiping mean for movementbetween a solvent wiping position and an inoperative position. 3.Printing apparatus according to claim 2, and including: f. recessedsurface means on said cylinder for receiving the end clamps of saidblanket means, and g. an elongated strip of absorbent material withinsaid recessed surface means, constituting said solvent absorbent meansand extending longitudinally of the cylinder and having a peripheralextent less than that of said recessed surface means.
 4. Printingapparatus according to claim 3, and including part cylindrical solventpermeable means having the same radius and center of curvature as saidblanket means, said absorbent strip being mounted on said solventpermeable means radially inward thereof.
 5. Printing apparatus accordingto claim 4, wherein said solvent permeable means comprises: h. anelongate plate, and j. passage means extending through said plate indirections radial with respect to the cylinder
 6. Printing apparatusaccording to claim 2, wherein said wiping means comprises a wiper bladeextending parallel to the axis of said cylinder, and wherein theinoperative position of said pivotable means is a position in which saidwiper blade is withdrawn from contact with said cylinder.
 7. Printingapparatus according to claim 2, wherein said solvent applying meanscomprises: k. a roller; l. solvent absorbent surface means on saidroller; m. solvent bath means for introducing ink solvent to saidabsorbent surface means; and n. means for pivotally mounting said rollerfor movement between a solvent applying position in contact with saidcylinder and an inoperative position out of contact with said cylinder.8. Printing apparatus according to claim 7, wherein said pivotablesupport means also carries said solvent wiping means.
 9. Printingapparatus according to claim 7, and including means for rotating thesolvent applying roller when in contact with the cylinder.
 10. Printingapparatus according to claim 9, wherein said roller rotating meansdrives the applying roller for rotation in the same direction ofrotation as that of the cylinder in use of the apparatus.